RN here. May I ask - is this a simple dressing, or a complicated dressing? Will you have all the proper supplies needed for the dressing change? How many times will it need to be done while you’re there?
Sometimes families learn how to do things like that at home when leaving the hospital, say. (And imagining that could possibly come into play here, too.) The current nurse who’s doing the dressing may be able to teach you how, especially if it’s a simple dressing change. That might be the easiest way. (Sometimes families who’ve been doing it for a while know more about it than a brand new person coming in, anyway.)
If worse comes to worst you could probably take him to an ER, but there are some downsides to that (long wait, germ factor, ? Insurance issues, etc.)
Perhaps your current home agency might have more ideas about referring him to somewhere down there, but that could get complicated, unfortunately. As someone who fully appreciates the value of someone who’s ill getting away for a bit with family, I sure hope you can find someone who can help.